Conductive heat transport cooling system and method for a multi-component electronics system

ABSTRACT

A conductive heat transport cooling system and method are provided for cooling primary and secondary heat generating components of an electronics system. The cooling system includes a liquid-based cooling subsystem including at least one liquid-cooled cold plate physically coupled to at least one primary heat generating component of the electronics system, and a thermally conductive coolant-carrying tube coupled to and in fluid communication with the at least one liquid-cooled cold plate. A thermally conductive auxiliary structure is coupled to the coolant-carrying tube and to at least one secondary heat generating component of the electronics system. When in use, the thermally conductive auxiliary structure provides conductive heat transport from the at least one secondary heat generating component to the at least one thermally conductive coolant-carrying tube coupled thereto, and hence via convection to liquid coolant passing therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application contains subject matter which is related to the subjectmatter of the following applications, each of which is assigned to thesame assignee as this application and each of which is herebyincorporated herein by reference in its entirety:

“Hybrid Cooling System and Method for a Multi-Component ElectronicsSystem”, Campbell et al., Ser. No. 11/539,902, filed Oct. 10, 2006;

“Method of Assembling a Cooling System for a Multi-Component ElectronicsSystem”, Campbell et al., Ser. No. 11/539,907, filed Oct. 10, 2006;

“Liquid-Based Cooling System for Cooling a Multi-Component ElectronicsSystem”, Campbell et al., Ser. No. 11/539,910, filed Oct. 10, 2006;

“Method and Apparatus for Mounting a Heat Sink in Thermal Contact withan Electronic Component”, Colbert et al, Ser. No. 11/201,972, filed Aug.11, 2005, and published on Feb. 15, 2007 as U.S. Patent Publication No.US 2007/0035937 A1; and

“Heatsink Apparatus for Applying a Specified Compressive Force to anIntegrated Circuit Device”, Colbert et al, Ser. No. 11/460,334, filedJul. 27, 2006, and published on Jan. 31, 2008 as U.S. Patent PublicationNo. US 2008/0024991 A1.

TECHNICAL FIELD

The present invention relates in general to cooling an electronicssystem, and more particularly, to a conductive heat transport basedcooling approach which facilitates cooling of secondary heat generatingcomponents of an electronics system using one or more thermallyconductive auxiliary structures coupled to a thermally conductivecoolant-carrying tube facilitating passage of liquid coolant through oneor more liquid-cooled cold plates coupled to one or more primary heatgenerating components of the electronics system to be cooled.

BACKGROUND OF THE INVENTION

The power dissipation of integrated circuit chips, and the modulescontaining the chips, continues to increase in order to achieveincreases in processor performance. This trend poses a cooling challengeat both the module and system level. Increased air flow rates are neededto effectively cool high power modules and to limit the temperature ofair exhausted into the computer center.

In many large server applications, processors along with theirassociated electronics (e.g., memory, disk drives, power, etc.), arepackaged in removable drawer configurations stacked or aligned within arack or frame. In other cases, the electronics may be in fixed locationswithin the rack or frame. Typically, the components are cooled by airmoving in parallel air flow paths, usually front-to-back, impelled byone or more air moving devices (e.g., fans or blowers). In some cases itmay be possible to handle increased power dissipation within a singledrawer by providing greater air flow, for example, through the use of amore powerful air moving device or by increasing the rotational speed(i.e., RPM) of an existing air moving device. However, this approach isbecoming unmanageable at the frame level in the context of a computerinstallation (e.g., data center).

The sensible heat load carried by the air exiting the frame willeventually exceed the ability of room air conditioning to effectivelyhandle the load. This is especially true for large installations of“server farms” or large banks of computer frames close together. In suchinstallations, not only will the room air conditioning be challenged,but the situation may also result in recirculation problems with somefraction of the “hot” air exiting one frame being drawn into the airinlet of the same or a nearby frame. Furthermore, while the acousticnoise level of a powerful (or higher RPM) air moving device in a singledrawer may be within acceptable acoustic limits, because of the numberof air moving devices in the frame, the total acoustic noise at theframe level may not be acceptable. In addition, the conventionalopenings in the frame for the entry and exit of air flow make itdifficult, if not impossible to provide effective acoustic treatment toreduce the acoustic noise level outside the frame. Finally, as operatingfrequencies continue to increase, electromagnetic cross talk betweentightly spaced computer frames is becoming a problem largely due to thepresence of the openings in the covers.

SUMMARY OF THE INVENTION

The shortcomings of the prior art are overcome, and additionaladvantages are realized through the provision, in one aspect, of anenhanced cooling system for a multi-component electronics system. Themulti-component electronics system includes at least one primary heatgenerating component to be cooled and at least one secondary heatgenerating component to be cooled. The cooling system includes aliquid-based cooling subsystem and a thermally conductive auxiliarystructure. The liquid-based cooling subsystem includes at least oneliquid-cooled cold plate configured to couple to the at least oneprimary heat generating component to be cooled. The liquid-based coolingsubsystem further includes at least one thermally conductivecoolant-carrying tube coupled to and in fluid communication with the atleast one liquid-cooled cold plate for facilitating passage of liquidcoolant through the at least one liquid-cooled cold plate. The thermallyconductive auxiliary structure is coupled to the at least one thermallyconductive coolant-carrying tube and is configured to couple to the atleast one secondary heat generating component to be cooled. When thecooling system is in use with the at least one liquid-cooled cold platecoupled to the at least one primary heat generating component to becooled and the thermally conductive auxiliary structure coupled to theat least one secondary heat generating component to be cooled, thethermally conductive auxiliary structure provides conductive heattransport from the at least one secondary heat generating component tothe at least one thermally conductive coolant-carrying tube coupledthereto and hence via convection to liquid coolant passing therethrough.

In another aspect, a cooled electronics system is provided whichincludes at least one electronics drawer containing multiple components,and a cooling system for cooling the multiple components. Theelectronics drawer includes at least one primary heat generating and atleast one secondary heat generating component to be cooled. The coolingsystem includes a liquid-based cooling subsystem and a thermallyconductive auxiliary structure. The liquid-based cooling subsystemincludes at least one liquid-cooled cold plate coupled to the at leastone primary heat generating component to be cooled, and at least onethermally conductive coolant-carrying tube coupled to and in fluidcommunication with the at least one liquid-cooled cold plate forfacilitating passage of liquid coolant through the at least oneliquid-cooled cold plate. The thermally conductive auxiliary structureis coupled to the at least one thermally conductive coolant-carryingtube and is coupled to the at least one secondary heat generatingcomponent to be cooled. When in use, the thermally conductive auxiliarystructure provides conductive heat transport from the at least onesecondary heat generating component to the at least one thermallyconductive coolant-carrying tube coupled thereto, and hence viaconvection to liquid coolant passing therethrough.

In a further aspect, a method of fabricating a cooling system isprovided for a multi-component electronics system. The method includes:providing a liquid-based cooling subsystem comprising at least oneliquid-cooled cold plate configured to physically couple to at least oneprimary heat generating component of the multi-component electronicssystem for liquid-based cooling thereof, the liquid-based coolingsubsystem further including at least one thermally conductivecoolant-carrying tube coupled to and in fluid communication with the atleast one liquid-cooled cold plate for facilitating passage of liquidcoolant through the at least one liquid-cooled cold plate; and couplinga thermally conductive auxiliary structure to the at least one thermallyconductive coolant-carrying tube, the thermally conductive auxiliarystructure being configured to couple to at least one secondary heatgenerating component of the multi-component electronics system. When thecooling system is in use, with the at least one liquid-cooled cold platecoupled to the at least one primary heat generating component to becooled and the thermally conductive auxiliary structure coupled to theat least one secondary heat generating component to be cooled, thethermally conductive auxiliary structure provides conductive heattransport from the at least one secondary heat generating component tothe at least one thermally conductive coolant-carrying tube coupledthereto, and hence via convection to liquid coolant passingtherethrough.

Further, additional features and advantages are realized through thetechniques of the present invention. Other embodiments and aspects ofthe invention are described in detail herein and are considered a partof the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 depicts one embodiment of a conventional air-cooled electronicsframe with heat generating electronic components disposed in removableelectronics drawers;

FIG. 2 is a plan view of one embodiment of an electronics drawer layoutillustrating multiple electronic components to be cooled, in accordancewith an aspect of the present invention;

FIG. 3 is a plan view of the electronics drawer layout of FIG. 2illustrating one embodiment of a cooling system for cooling thecomponents of the drawer, in accordance with an aspect of the presentinvention;

FIG. 3A is a partially enlarged view of the assembly of FIG. 3 expandedwithin circle 3A of FIG. 3, in accordance with an aspect of the presentinvention;

FIG. 3B is a partial cross-sectional elevational view of the structureof FIG. 3A taken along line 3B-3B, in accordance with an aspect of thepresent invention;

FIG. 4A is a partial elevational view of an air-cooled heat sink andsecondary heat generating component of the electronics drawer componentlayout of FIG. 3, and depicting multiple thermally conductive auxiliarystructures of a cooling system disposed to cool by conductive heattransport the air-cooled heat sink and hence the secondary heatgenerating component coupled thereto, in accordance with an aspect ofthe present invention;

FIG. 4B is an elevational view of one thermally conductive auxiliarystructure depicted in FIG. 4A, in accordance with an aspect of thepresent invention;

FIG. 5A is a partial elevational view of a secondary heat generatingcomponent of the electronics drawer component layout of FIG. 3, andshowing an alternate embodiment of multiple thermally conductiveauxiliary structures of a cooling system disposed to cool by conductiveheat transport the secondary heat generating component, in accordancewith an aspect of the present invention;

FIG. 5B is an elevational view of one thermally conductive auxiliarystructure depicted in FIG. 5A, in accordance with an aspect of thepresent invention;

FIG. 6A is a partial cross-sectional elevational view of the electronicsdrawer component layout of FIG. 3, and depicting folded fin structuresof a thermally conductive auxiliary structure of a cooling systemdisposed to cool by conductive heat transport selected secondary heatgenerating electronic components of the electronics drawer, inaccordance with an aspect of the present invention; and

FIG. 6B is an enlarged partial depiction of the folded fin structures ofthe cooling system of FIG. 6A, in accordance with an aspect of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

As used herein “electronics system” comprises any system containing oneor more heat generating components of a computer system or otherelectronics unit requiring cooling. The terms “electronics rack”,“electronics frame”, and “frame” are used interchangeably, and includeany housing, rack, compartment, blade chassis, etc., having heatgenerating components of a computer system or electronics system and maybe for example, a stand-alone computer processor having high, mid or lowend processing capability. In one embodiment, an electronics framecomprises multiple electronics drawers, each having multiple heatgenerating components disposed therein requiring cooling. “Electronicsdrawer” refers to any sub-housing, blade, book, drawer, node,compartment, etc., having multiple heat generating electronic componentsdisposed therein. Each electronics drawer of an electronics frame may bemovable or fixed relative to the electronics frame, with rack mountedelectronics drawers and blades of a blade center system being twoexamples of drawers of an electronics frame to be cooled.

“Electronic component” refers to any heat generating electroniccomponent of, for example, a computer system or other electronics unitrequiring cooling. By way of example, an electronic component maycomprise one or more integrated circuit chips and/or other electronicdevices to be cooled, including one or more processor modules, memorymodules and memory support modules. As used herein, “primary heatgenerating component” refers to a primary heat generating electroniccomponent within the electronics system (with a processor module beingone example), while “secondary heat generating component” refers to anelectronic component of the electronics system generating less heat thanthe primary heat generating component to be cooled (with memory modulesand memory support modules being examples of secondary components to becooled). Further, as used herein, the term “liquid-cooled cold plate”refers to any conventional thermally conductive structure having aplurality of channels or passageways formed therein for flowing ofliquid coolant therethrough.

As shown in FIG. 1, in rack-mounted configurations typical in the priorart, a plurality of air moving devices 111 (e.g., fans or blowers)provide forced air flow 115 needed to cool the electronic components 112within the electronics drawers 113 of the frame 100. Cool air is takenin through a louvered inlet cover 114 in the front of the frame andexhausted out a louvered outlet cover 116 in the back of the frame.

FIG. 2 illustrates one embodiment of a multi-component electronicsdrawer 213 having a component layout in accordance with an aspect of thepresent invention. Electronics drawer 213 includes one or more airmoving devices 211 (e.g., fans or blowers) which provide forced air flow215 across the multiple electronic components 212 within electronicsdrawer 213. Cool air is taken in through a front 231 of electronicsdrawer 213 and exhausted out a back 233 of the electronics drawer. Inthis embodiment, the multiple electronic components to be cooled 212include processor modules disposed below air-cooled heat sinks 220, aswell as (by way of example) arrayed memory modules 230 (such asair-cooled dual in-line memory module (DIMM) packages), and multiplerows of memory support modules 232 disposed between the arrayed memorymodules.

Those skilled in the art will note that although described herein inassociation with DIMM packages, and their memory support modules, theconcepts presented are applicable to facilitating cooling of anysecondary heat generating component within an electronics system. Again,the terms “primary heat generating component” and “secondary heatgenerating component” are used to differentiate between heat generatingcapabilities of components within the electronics system. By way ofexample, processor modules typically generate more heat than, forexample, memory modules or memory support modules, and therefore aredeemed primary heat generating components within the electronics system,while the memory modules and memory support modules are referred toherein as secondary heat generating components.

As illustrated further in one or more of the initially incorporatedapplications (as well as in FIGS. 6A & 6B hereof), each DIMM packageincludes a short rectangular substrate plugged into a connector on amotherboard at the bottom of the electronics drawer, and projects upwardfrom the motherboard. Memory chips are surface-mounted in a line on theDIMM substrate parallel to the air flow direction through theelectronics drawer. A number of DIMMs are pluggable in closely spacedposition across the electronics drawer, forming multiple air flowchannels or passageways between the DIMMs which extend at leastpartially through the electronics drawer.

In order to provide greater performance, it will eventually be necessaryto increase processor chip powers beyond the point where forcedair-cooling is feasible as a solution. Because of their level of powerdissipation, the memory support modules and/or memory modules themselvesmay also require the application of auxiliary cooling to be effectivelycooled. To meet these increased cooling demands, a cooling system may beprovided with a liquid-based cooling subassembly including at least oneliquid-cooled cold plate physically coupled to the at least one primaryheat generating component (e.g., processor module) to be cooled.

FIG. 3 is a simplified depiction of the electronics drawer componentlayout of FIG. 2, with such a cooling system shown. In the embodimentdepicted, the cooling system includes a liquid-based cooling subsystemand multiple sets of thermally conductive coolant-carrying tubes, inaccordance with an aspect of the present invention.

More particularly, FIG. 3 depicts one embodiment of an electronicsdrawer 313 component layout wherein one or more air moving devices 311provide forced air flow 315 to cool multiple components 312 withinelectronics drawer 313. Cool air is taken in through a front 331 andexhausted out a back 333 of the drawer. The multiple components 312 tobe cooled include multiple processor modules to which liquid-cooled coldplates 320 are coupled, as well as multiple arrays of memory modules 330(e.g., dual in-line memory modules (DIMMs) configured as described abovein connection with memory modules 230 of FIG. 2) and multiple rows ofmemory support modules (332, FIG. 3B) (e.g., DIMM control modules) towhich air-cooled heat sinks 334 are coupled. In the embodimentillustrated, memory modules 330 and the memory support modules arepartially arrayed near front 331 of electronics drawer 313, andpartially arrayed near back 333 of electronics drawer 313. Also, in theembodiment of FIG. 3, memory modules 330 and the memory support modules(below air-cooled heat sinks 334) are cooled by air flow 315 across theelectronics drawer.

The thermally conductive coolant-carrying tubes in the embodiment ofFIG. 3 comprise sets of coolant-carrying tubes, with each set includinga thermally conductive coolant supply tube 340 and a thermallyconductive coolant return tube 342. In this example, each set of tubesprovides liquid coolant to a pair of cold plates 320 (coupled to a pairof processor modules). Coolant flows into a first cold plate of the pairvia the thermally conductive coolant supply tube 340 and from the firstcold plate to the second cold plate via a bridge tube or line 341, whichmay or may not be thermally conductive. From the second cold plate ofthe pair, coolant is returned through the respective thermallyconductive coolant return tube 342. In an alternate embodiment, only thesupply tube 340 or the return tube 342 is thermally conductive, e.g.,fabricated of a metal (such as copper or aluminum), with the other tubebeing, for example, a flexible, non-thermally conductivecoolant-carrying line or hose. The auxiliary structures presented hereinbelow couple to at least one thermally conductive coolant-carrying tube,which itself is coupled to and in fluid communication with at least oneliquid-cooled cold plate (coupled to at least one primary heatgenerating component to be cooled).

In an alternate implementation, eight processor modules might bedisposed within the electronics drawer, each requiring a respectiveliquid-cooled cold plate 320 coupled thereto, as well as associatedcoolant-carrying tubes for facilitating passage of liquid coolantthrough the liquid-cooled cold plates. In either embodiment, an inletheader and an outlet header may be employed within the electronicsdrawer to facilitate distribution of liquid coolant to and return of theliquid coolant from the liquid-cooled cold plates. Ultimately, only twotubes or valves may extend from each electronics drawer of a frame,which are in communication with the inlet and outlet headers. Further,by way of specific example, the liquid coolant passing through theliquid-based cooling subsystem may be chilled water.

FIGS. 3A & 3B depict in greater detail one aspect of the cooling systemof FIG. 3. As best shown in FIG. 3B, memory support module 332 iscoupled to a substrate 300 via, for example, appropriate electricalinterconnect 302. A thermal interface material 304 (such as a thermalpaste) couples air-cooled heat sink 334 to memory support module 332.Air-cooled heat sink 334 includes a plurality of upwardly projectingthermally conductive fins 335. In this embodiment, the plurality ofthermally conductive fins 335 are sized to accommodate overhead athermally conductive coolant supply tube 340 and a thermally conductivecoolant return tube 342 providing liquid coolant to one or moreliquid-cooled cold plates of the cooling system. A cover 306 enclosesthe assembly.

One disadvantage of implementing a cooling system in a manner such asdepicted in FIGS. 3, 3A & 3B is that the fins of the air-cooled heatsinks 334 need to be modified to accommodate overhead the liquid coolantplumbing for the drawer. Reduction in the size of these thermallyconductive fins can decrease thermal performance of the air-cooled heatsinks, and consequently, result in higher temperatures at the circuitryof the memory support modules. Thus, in one aspect, provided herein arecooling systems which address cooling of secondary heat generatingcomponents whose traditional air-cooling capability may be diminisheddue to the inclusion of liquid coolant hardware within an electronicsdrawer. In another aspect, presented herein are cooling systems whichfacilitate cooling of additional, secondary heat generating componentssuch as memory modules (e.g., dual in-line memory modules). In view ofthe above-noted DIMM geometry and close spacing, an enhanced coolingsystem and method are also presented which utilize a thermallyconductive auxiliary structure extending outward over the DIMMs andcoupled to one or more of the thermally conductive coolant-carryingtubes (facilitating passage of coolant to the liquid-cooled cold platesattached to the processor modules). As used herein, the phrases“coupled” and “physically coupled” refer to either a direct or indirectphysical coupling (for example, of the auxiliary structure to at leastone thermally conductive coolant-carrying tube).

In the embodiments described herein, the cooling system and methodpresented employ conductive heat transport from at least one secondaryheat generating component to at least one thermally conductivecoolant-carrying tube using one or more thermally conductive auxiliarystructures, wherein the at least one thermally conductivecoolant-carrying tube facilitates passage of liquid coolant through oneor more liquid-cooled cold plates configured to couple to one or moreprimary heat generating components of an electronics system to becooled. By way of example, FIGS. 4A-5B depict alternate embodiments of athermally conductive auxiliary structure for facilitating conductiveheat transport between one or more memory support modules and one ormore thermally conductive coolant-carrying tubes, while FIGS. 6A & 6Bdepict one embodiment of a thermally conductive auxiliary structurewhich facilitates conductive heat transport from multiple memory modulesto one or more thermally conductive coolant-carrying tubes. In theseembodiments, the memory support modules and the memory modules areexemplary secondary heat generating components to be cooled, with theprocessor modules being an exemplary of primary heat generatingcomponents to be cooled of an electronics system (such as a highperformance server application).

Referring first to FIGS. 4A & 4B, memory support module 332 is againsupported by and electrically connected to a substrate 300 and employsan air-cooled heat sink 334 having a plurality of thermally conductivefins 335. The cooling system includes, in this embodiment, multiplethermally conductive auxiliary structures 410, 412 which provide directconductive heat transport between air-cooled heat sink 334 and thermallyconductive coolant supply and return tube 340, 342. Thermally conductiveauxiliary structures 410, 412 (which are shown contacting cover 306) areeach, in one example, a block- or rectangular-shaped structure having anopening (such as opening 415 in thermally conductive auxiliary structure412 shown in FIG. 4B) sized and configured to accommodate a respectivethermally conductive coolant distribution tube 340, 342, which assumesthat both the supply and return tubes are thermally conductivecoolant-carrying tubes. In an alternate example, thermally conductiveauxiliary structures 410, 412 each comprise multiple sections orcomponents assembled to surround the respective thermally conductivecoolant distribution tube 340, 342. Fabricating the auxiliary structuresof multiple sections would facilitate retrofitting an existing coolingsystem with the auxiliary cooling presented herein. Further, as avariation, vapor chambers, heat pipes or liquid-filled structures couldbe integrated within the thermally conductive auxiliary structures.Since thermally conductive auxiliary structure 410 encircles, and isphysically coupled to, coolant supply tube 340, and thermally conductiveauxiliary structure 412 encircles, and is physically coupled to, coolantreturn tube 342, the auxiliary structures are spaced apart 414 toprevent direct thermal coupling between the thermally conductive coolantsupply and return tubes. Note also that in this example, it is assumedthat cover 306 is fabricated of a non-thermally conductive material.

Each thermally conductive auxiliary structure 410, 412 includes aplurality of channels (such as channels 420 in thermally conductiveauxiliary structure 412 shown in FIG. 4B) positioned and configured toaccommodate respective ones of the plurality of thermally conductivefins 335 of air-cooled heat sink 334. These channels accommodate therespective fins of the air-cooled heat sink in such a manner that thefins physically couple to the auxiliary structure. As noted, andalthough not fully shown, structures 410, 412 are each configured (inone example) as a unitary block of thermally conductive material (e.g.,copper or aluminum) sized to extend over at least a portion of theair-cooled heat sink(s) to receive auxiliary cooling. For example, eachmemory support module in the rows of memory support modules having thethermally conductive coolant distribution tubes extending overhead mayhave one or more thermally conductive auxiliary structures physicallycoupled thereto to provide conductive heat transport from the air-cooledheat sinks coupled thereto to the thermally conductive coolant-carryingtube(s), and hence via convection to liquid coolant flowing through thetube(s).

In one specific embodiment, thermally conductive auxiliary structurescan each be fabricated as a rectangular sleeve having a cylindricalcavity, with the rectangular sleeves being metallurgically joined to thethermally conductive coolant-carrying tubes. The channels formed in theauxiliary structures may be formed as grooves or slots cut into, forexample, the planar surface of the structure facing an air-cooled heatsink attached to the secondary heat generating component to be cooled.These channels in the auxiliary structure mate with the fins of the heatsink to ensure good thermal contact and to allow heat to be extractedfrom the tips of the fins for transport ultimately to the liquid coolantpassing through the coolant-carrying tubes. Thus, in this embodiment,heat dissipated by the secondary heat generating component (e.g., suchas a memory controller chip) is removed by a combination of two modes;i.e., via convective heat transfer to air, and via conductive heattransfer through the auxiliary structure (ultimately to liquid coolantflowing through the thermally conductive coolant-carrying tubes). Athermal interface material, such as a thermally conductive grease, maybe employed in the channels of the auxiliary structures to facilitateconductive heat transport from the fins of the air-cooled heat sinks tothe auxiliary structures. As a variation, the auxiliary structures neednot be metallurgically joined to the coolant-carrying tubes, but rather,the auxiliary structures may be press-fitted (e.g., if one-piece) orclamped (e.g., if two-pieces) onto the coolant-carrying tubes using athermal interface material to ensure good contact for conductive heattransport.

FIGS. 5A & 5B depict an alternate embodiment of a thermally conductiveauxiliary structure (or conduction cooler), in accordance with an aspectof the present invention.

As shown, a memory support module 332 is again supported by andelectrically coupled to a substrate 300. In this case, the air-cooledheat sink of FIGS. 4A & 4B is removed and the thermally conductiveauxiliary structures 510, 512 are sized and configured to at leastpartially couple to memory support module 332 across a thermal interfacematerial layer 500. Each thermally conductive auxiliary structure 510,512 is, in one example, a block- or rectangular-shaped structure (orrectangular sleeve_having a cylindrical opening (such as opening 520 inauxiliary structure 512 of FIG. 5B) sized and positioned to accommodatea respective one of the thermally conductive coolant-carrying tubes 340,342. In an alternate example, thermally conductive auxiliary structures510, 512 each comprise multiple sections or components assembled tosurround the respective thermally conductive coolant distribution tube340, 342. Fabricating the auxiliary structures of multiple sectionswould facilitate retrofitting an existing cooling system with theauxiliary cooling presented herein. Further, as a variation, vaporchambers, heat pipes or liquid-filled structures could be integratedwithin the thermally conductive auxiliary structures. Auxiliarystructures 510, 512 also contact (in this embodiment) cover 306, whichis again assumed to be fabricated of a non-thermally conductivematerial. An air space 514 is provided between thermally conductiveauxiliary structure 510 encircling thermally conductive coolant-carryingtube 340 and thermally conductive auxiliary structure 512 encirclingthermally conductive coolant return tube 342 to prevent conductive heattransport therebetween.

As with the embodiment of FIGS. 4A & 4B, the auxiliary structure (e.g.,block or sleeve) may be metallurgically joined to the respectivecoolant-carrying tube, or alternatively, press-fitted or clamped to thetube employing a thermal interface material between the auxiliarystructure and tube to ensure a good thermal interface. Heat isconductively transported from the secondary heat generating component(e.g., memory support module 332) to the thermally conductivecoolant-carrying tube, and hence via convection to liquid coolantflowing through the coolant-carrying tube, thereby facilitating coolingof the secondary heat generating component employing the liquid coolantprovided for the liquid-cooled cold plate coupled to the primary heatgenerating component to be cooled.

FIGS. 6A & 6B depict a further variation on a cooling system employingsecondary conductive heat transport, in accordance with an aspect of thepresent invention.

In this embodiment, a plurality of DIMM packages (or memory modules 330)plug into and extend upward from a support substrate 600. The DIMMpackages are spaced, with air flow passageways defined between the DIMMpackages for cooling thereof. The cooling system includes a thermallyconductive auxiliary structure 610 which, in this embodiment, includes ametal plate configured to accommodate and physically couple to one ormore of the thermally conductive coolant-carrying tubes. In theembodiment of FIGS. 6A & 6B, thermally conductive auxiliary structure610 is configured to accommodate at least thermally conductive coolantsupply tube 340. A mounting bracket 615 removably secures thermallyconductive auxiliary structure 610 to thermally conductive coolantsupply tube 340 employing, for example, multiple connectors 616 (such asthread screws). A plurality of thermally conductive folded finstructures 620 extend downward (in this embodiment) from thermallyconductive auxiliary structure 610 into the air flow passageways definedbetween adjacent DIMM packages. Those skilled in the art should notethat (as used herein) the terms “upward” and “downward” are relative andcan be reversed, depending on the implementation.

As best shown in FIG. 6B, each folded fin structure 620 is formed of acontinuous thin conductive metal sheet folded to form two opposing sidesdrawn together at the top and bottom. If a force is applied to the outerface of either side, the folded fin structure acts in a manner similarto two leaf springs joined together at their ends. The folded finstructures are joined (for example, employing a thermal epoxy, solder orbraze) to a base plate of the auxiliary structure so that a folded finstructure projects into each air flow passageway defined betweenadjacent memory modules (e.g., DIMM packages) to be cooled. Duringassembly, the auxiliary structure is brought down into the electronicsdrawer so that the folded fin structures enter the air flow passagewaysbetween adjacent DIMM packages. Each folded fin structure itselfincludes a smaller air flow passage 630 defined between the opposingsidewalls of the structure.

As shown in FIGS. 6A & 6B, the folded fin structures are rounded attheir bottom to permit ease of entry of the fin structure betweenopposing memory chips on adjacent DIMM packages. As the cooling assemblyis further inserted, the folded fin structures compress slightly,allowing full insertion of the folded fin structures between the DIMMpackages. Upon completion of the assembly process, the face of eachfolded fin sidewall is physically coupled to an outer surface of theadjacent memory chip of an adjacent DIMM package, providing a thermalconduction path from the memory chip to the folded fin structure. Inoperation, heat flows by thermal conduction from each memory module toits contacting folded fin structure, and a certain amount of this heatis conducted via the fin structure to the base plate, and hence to thethermally conductive coolant-carrying tube coupled to the base plate.From the thermally conductive coolant-carrying tube, heat flows byconvection to liquid coolant flowing through the tube. The remainder ofthe heat conducted into the folded fin structure is transferred byforced convection to air flowing in the open space 630 between theopposing sidewalls of the folded fin structure. Additional heat is alsorejected from the remaining surfaces of the adjacent DIMM packages toair flowing in contact with the surfaces.

The thermally conductive auxiliary structures of the embodiments ofFIGS. 6A-6B can be attached via mounting plates 615 joined to theunderside of the coolant distribution line(s) by means of, for example,a thermally conductive epoxy, solder or braze around the lower half ofthe coolant-carrying pipe(s). The mounting plates extend outwards fromthe pipes to provide increased thermal contact area with the undersideof the thermally conductive auxiliary structure, thereby reducingthermal contact resistance between the auxiliary structure(s) and thepipe(s). In one embodiment, the auxiliary structure and mounting platesare joined via threaded mechanical screws.

It should be also noted that it is sometimes necessary to replace or addDIMMs to a node in the field. Thus, one feature of the cooling systemsdescribed herein is that they allow servicing in the field. This isaccomplished by withdrawing the node (i.e., electronics drawer) from theelectronics rack and removing (i.e., in the embodiment of FIGS. 6A & 6B)the attachment screws from the thermally conductive auxiliary structure.The auxiliary structure may then be lifted and removed to allow accessto unplug or plug DIMMs into the drawer's motherboard. As anotherfeature of the cooling system disclosed herein, the system not onlyenhances the cooling of the secondary components (e.g., DIMM packages),it reduces the heat load on the customer room air conditioning byfurther reducing heat that is transferred to the air exiting each drawerof the electronics frame.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions and the like can bemade without departing from the spirit of the invention, and that theseare therefore considered to be within the scope of the invention asdefined in the following claims.

1. A cooling system for a multi-component electronics system comprisingat least one primary heat generating component to be cooled and at leastone secondary heat generating component to be cooled, the cooling systemcomprising: a liquid-based cooling subsystem comprising at least oneliquid-cooled cold plate configured to couple to the at least oneprimary heat generating component to be cooled of a multi-componentelectronics system, the liquid-based cooling subsystem furthercomprising at least one thermally conductive coolant-carrying tubecoupled to and in fluid communication with the at least oneliquid-cooled cold plate for facilitating passage of liquid coolantthrough the at least one liquid-cooled cold plate; a thermallyconductive auxiliary structure coupled to the at least one thermallyconductive coolant-carrying tube and configured to couple to the atleast one secondary heat generating component to be cooled, wherein whenthe cooling system is in use with the at least one liquid-cooled coldplate coupled to the at least one primary heat generating component tobe cooled and the thermally conductive auxiliary structure coupled tothe at least one secondary heat generating component to be cooled, thethermally conductive auxiliary structure provides conductive heattransport from the at least one secondary heat generating component tothe at least one thermally conductive coolant-carrying tube coupledthereto, and hence via convection to liquid coolant passingtherethrough; and at least one air-cooled heat sink configured to coupleto the at least one secondary heat generating component to be cooled,the at least one air-cooled heat sink comprising a plurality ofthermally conductive fins, and wherein the cooling system furthercomprises multiple thermally conductive auxiliary structures, eachthermally conductive auxiliary structure comprising a rectangular-shapedstructure surrounding a thermally conductive coolant-carrying tube ofthe at least one thermally conductive coolant-carrying tube, and atleast partially aligned over and coupled to the at least one air-cooledheat sink when the cooling system is employed to cool themulti-component electronics system, with the at least one air-cooledheat sink coupled to the at least one secondary heat generatingcomponent to be cooled.
 2. The cooling system of claim 1, wherein theliquid-based cooling subsystem comprises multiple thermally conductivecoolant-carrying tubes, the multiple thermally conductivecoolant-carrying tubes comprising a thermally conductive coolant supplytube and a thermally conductive coolant return tube, and wherein eachthermally conductive auxiliary structure is configured to couple to arespective thermally conductive coolant-carrying tube of theliquid-based cooling subsystem.
 3. The cooling system of claim 2,wherein each thermally conductive auxiliary structure comprises multiplechannels formed in at least one surface thereof and configured toreceive and couple to respective thermally conductive fins of theplurality of thermally conductive fins of the at least one air-cooledheat sink when the cooling system is employed to cool themulti-component electronics system, with each thermally conductiveauxiliary structure physically coupling to the respective thermallyconductive fins of the at least one air-cooled heat sink and providingconductive heat transport from the at least one air-cooled heat sink tothe respective thermally conductive coolant-carrying tube coupled to thethermally conductive auxiliary structure, and thereafter via convectionto liquid coolant passing through the respective thermally conductivecoolant-carrying tube.
 4. The cooling system of claim 3, wherein a firstthermally conductive auxiliary structure of the multiple thermallyconductive auxiliary structures surrounds the thermally conductivecoolant supply tube and a second thermally conductive auxiliarystructure of the multiple thermally conductive auxiliary structuressurrounds the thermally conductive coolant return tube, and wherein thefirst thermally conductive auxiliary structure and the second thermallyconductive auxiliary structure both couple to the at least oneair-cooled heat sink and are spaced apart to prevent direct thermalconduction therebetween.
 5. The cooling system of claim 3, wherein eachthermally conductive auxiliary structure and the respective thermallyconductive fins of the plurality to thermally conductive fins extendingfrom the at least one air-cooled heat sink define air channelstherebetween, and wherein the cooling system further comprises an airmoving device for establishing air flow across the multiple componentsof the electronics system, the air moving device establishing air flowthrough the air channels defined between each thermally conductiveauxiliary structure and the respective thermally conductive finsextending from the at least one air-cooled heat sink.
 6. The coolingsystem of claim 3, wherein each thermally conductive auxiliary structureincludes a cylindrical opening sized to receive the respective thermallyconductive coolant-carrying tube.
 7. The cooling system of claim 1,wherein the thermally conductive auxiliary structure includes aplurality of thermally conductive folded fin structures extending from asurface thereof, and wherein when the cooling system is employed to coolthe multi-component electronics system, with the at least oneliquid-cooled cold plate coupled to the at least one primary heatgenerating component to be cooled, at least one thermally conductivefolded fin structure of the plurality of thermally conductive folded finstructures couples to the at least one secondary heat generatingcomponent to be cooled.
 8. The cooling system of claim 7, wherein theplurality of thermally conductive folded fin structures each comprise anair flow passage therethrough, and wherein the multi-componentelectronics system comprises multiple secondary heat generatingcomponents to be cooled, the multiple secondary heat generatingcomponents to be cooled being arrayed on a substrate with air flowpassageways defined between adjacent secondary heat generatingcomponents of the multiple secondary heat generating components, andwherein when the cooling system is employed to cool the multi-componentelectronics system, at least some thermally conductive folded finstructures of the plurality of thermally conductive folded finstructures of the thermally conductive auxiliary structure extend intoair flow passageways defined between adjacent secondary heat generatingcomponents of the multiple secondary heat generating components to becooled and couple to the adjacent secondary heat generating componentsto provide conductive heat transport from the adjacent secondary heatgenerating components and to provide cooling of air flow passing throughthe air flow passages of the at least some thermally conductive foldedfin structures.
 9. The cooling system of claim 1, wherein theelectronics system comprises multiple secondary heat generatingcomponents to be cooled, and wherein the at least one primary heatgenerating component comprises at least one processor module to becooled, and the multiple secondary heat generating components comprisemultiple memory modules and multiple memory support modules arrayed on asubstrate, at least some memory support modules of the multiple memorysupport modules being aligned in at least one row, with the multiplememory modules being arrayed on at least one side thereof, and whereinwhen the cooling system is employed to cool the multi-componentelectronics system, the at least one thermally conductivecoolant-carrying tube extends over the at least one row of memorysupport modules, and wherein the thermally conductive auxiliarystructure is disposed to facilitate cooling of the at least one row ofmemory support modules.
 10. A cooling system for a multi-componentelectronics system comprising at least one primary heat generatingcomponent to be cooled and at least one secondary heat generatingcomponent to be cooled, the cooling system comprising: a liquid-basedcooling subsystem comprising at least one liquid-cooled cold plateconfigured to couple to the at least one primary heat generatingcomponent to be cooled of a multi-component electronics system, theliquid-based cooling subsystem further comprising at least one thermallyconductive coolant-carrying tube coupled to and in fluid communicationwith the at least one liquid-cooled cold plate for facilitating passageof liquid coolant through the at least one liquid-cooled cold plate; athermally conductive auxiliary structure coupled to the at least onethermally conductive coolant-carrying tube and configured to couple tothe at least one secondary heat generating component to be cooled,wherein when the cooling system is in use with the at least oneliquid-cooled cold plate coupled to the at least one primary heatgenerating component to be cooled and the thermally conductive auxiliarystructure coupled to the at least one secondary heat generatingcomponent to be cooled, the thermally conductive auxiliary structureprovides conductive heat transport from the at least one secondary heatgenerating component to the at least one thermally conductivecoolant-carrying tube coupled thereto, and hence via convection toliquid coolant passing therethrough; and wherein the liquid-basedcooling subsystem comprises multiple thermally conductivecoolant-carrying tubes, the multiple thermally conductivecoolant-carrying tubes comprising a thermally conductive coolant supplytube and a thermally conductive coolant return tube, and wherein thecooling system further comprises multiple thermally conductive auxiliarystructures, each thermally conductive auxiliary structure beingconfigured to couple to a respective thermally conductivecoolant-carrying tube of the liquid-based cooling subsystem, and eachthermally conductive auxiliary structure comprising a unitary structureat least partially aligned over and coupled to the at least onesecondary heat generating component to be cooled, wherein a firstthermally conductive auxiliary structure of the multiple thermallyconductive auxiliary structures surrounds the thermally conductivecoolant supply tube, and a second thermally conductive auxiliarystructure of the multiple thermally conductive auxiliary structuressurrounds the thermally conductive coolant return tube, the firstthermally conductive auxiliary structure and the second thermallyconductive auxiliary structure being spaced apart to prevent thermalconduction therebetween.
 11. The cooling system of claim 10, whereineach thermally conductive auxiliary structure further comprises acylindrical-shaped opening sized to receive the respective thermallyconductive coolant-carrying tube of the liquid-based cooling subsystem,and wherein each thermally conductive auxiliary structure is sized to atleast partially physically couple to the at least one secondary heatgenerating component to be cooled across a thermal interface materialwhen the cooling system is employed to cool the multi-componentelectronics system, and wherein each thermally conductive auxiliarystructure is fabricated of metal to facilitate conductive heat transportfrom the at least one secondary heat generating component to therespective thermally conductive coolant-carrying tube, and hence toliquid coolant passing therethrough via convection.
 12. A cooledelectronics system comprising: at least one electronics drawercontaining multiple heat generating components to be cooled, the atleast one electronics drawer comprising at least one primary heatgenerating component to be cooled and at least one secondary heatgenerating component to be cooled; and a cooling system for cooling themultiple components of the at least one electronics drawer, the coolingsystem comprising: a liquid-based cooling subsystem comprising at leastone liquid-cooled cold plate coupled to the at least one primary heatgenerating component to be cooled, the liquid-based cooling subsystemfurther including at least one thermally conductive coolant-carryingtube coupled to and in fluid communication with the at least oneliquid-cooled cold plate for facilitating passage of liquid coolantthrough the at least one liquid-cooled cold plate; a thermallyconductive auxiliary structure coupled to the at least one thermallyconductive coolant-carrying tube and coupled to the at least onesecondary heat generating component to be cooled, the thermallyconductive auxiliary structure providing conductive heat transport fromthe at least one secondary heat generating component to the at least onethermally conductive coolant-carrying tube, and hence via convection toliquid coolant passing therethrough; and at least one air-cooled heatsink coupled to the at least one secondary heat generating component tobe cooled, the at least one air-cooled heat sink comprising a pluralityof thermally conductive fins, and wherein the cooling system furthercomprises multiple thermally conductive auxiliary structures, eachthermally conductive auxiliary structure comprising a rectangular-shapedstructure surrounding a thermally conductive coolant-carrying tube ofthe at least one thermally conductive coolant-carrying tube, and atleast partially aligned over and coupled to the at least one air-cooledheat sink coupled to the at least one secondary heat generatingcomponent to be cooled.
 13. The cooled electronics system of claim 12,wherein the liquid-based cooling subsystem comprises multiple thermallyconductive coolant-carrying tubes, the multiple thermally conductivecoolant-carrying tubes comprising a thermally conductive coolant supplytube and a thermally conductive coolant return tube, and wherein eachthermally conductive auxiliary structure is configured to couple to arespective thermally conductive coolant-carrying tube of theliquid-based cooling subsystem.
 14. The cooled electronics system ofclaim 13, wherein each thermally conductive auxiliary structurecomprises multiple channels formed in at least one surface thereof andconfigured to couple to respective thermally conductive fins of theplurality of thermally conductive fins of the at least one air-cooledheat sink, with each thermally conductive auxiliary structure physicallycoupling to the respective thermally conductive fins of the at least oneair-cooled heat sink and providing conductive heat transport from the atleast one air-cooled heat sink to the respective thermally conductivecoolant-carrying tube surrounded by the thermally conductive auxiliarystructure, and thereafter via convection to liquid coolant passingthrough the respective thermally conductive coolant-carrying tube. 15.The cooled electronics system of claim 12, wherein the liquid-basedcooling subsystem comprises multiple thermally conductivecoolant-carrying tubes, the multiple thermally conductivecoolant-carrying tubes comprising a thermally conductive coolant supplytube and a thermally conductive coolant return tube, and wherein thecooling system further comprises multiple thermally conductive auxiliarystructures, each thermally conductive auxiliary structure being coupledto a respective thermally conductive coolant-carrying tube of theliquid-based cooling subsystem, and each thermally conductive auxiliarystructure comprising a unitary structure at least partially aligned overand coupled to the at least one secondary heat generating component tobe cooled, wherein a first thermally conductive auxiliary structure ofthe multiple thermally conductive auxiliary structures surrounds thethermally conductive coolant supply tube, and a second thermallyconductive auxiliary structure of the multiple thermally conductiveauxiliary structures surrounds the thermally conductive coolant returntube are spaced apart to prevent thermal conduction therebetween. 16.The cooled electronics system of claim 12, wherein the thermallyconductive auxiliary structure includes a plurality of thermallyconductive folded fin structures extending from a surface thereof, andwherein at least one thermally conductive folded fin structure of theplurality of thermally conductive folded fin structures couples to theat least one secondary heat generating component to be cooled.
 17. Thecooled electronics system of claim 16, wherein the plurality ofthermally conductive folded fin structures each comprise an air flowpassage therethrough, and wherein the multi-component electronics systemcomprises multiple secondary heat generating components to be cooled,the multiple secondary heat generating components to be cooled beingarrayed on a substrate with air flow passageways defined betweenadjacent secondary heat generating components of the multiple secondaryheat generating components, and wherein at least some thermallyconductive folded fin structures of the plurality of thermallyconductive folded fin structures extend into air flow passagewaysdefined between adjacent secondary heat generating components of themultiple secondary heat generating components to be cooled and couple tothe adjacent secondary heat generating components to provide conductiveheat transport from the adjacent secondary heat generating componentsand to provide cooling of air flow passing through the air flow passagesof the at least some thermally conductive folded fin structures.